1. Field of the Invention
The present application relates to a test apparatus, and more particularly, to a test apparatus for a liquid crystal display device and a test method of the liquid crystal display device.
2. Discussion of the Related Art
Although cathode-ray tubes (CRTs) have been widely used as a display device for a television, a measuring instrument or an information terminal, it is hard to apply the CRTs to reduced electronic products in size and weight because of their heavy weight and large volume. Recently, flat panel display (FPD) such as liquid crystal display (LCD) devices and plasma display panels (PDPs) have been the subject of research and development because of their superior thin profile and light weight as compared with the CRTs.
LCD devices include a liquid crystal panel having opposite two substrates and a liquid crystal layer between the two substrates. After first and second substrates, which include an array element and a color filter layer, respectively, are formed through repetition of a thin film deposition step, a photolithographic step and an etching step, a seal pattern is formed on one of the first and second substrates. The first and second substrates may be referred to as an array substrate and a color filter substrate, respectively. Next, the first and second substrates are attached, and the liquid crystal layer is formed between the first and second substrates to complete the liquid crystal panel. After polarizing plates and a driving circuit unit are attached to the liquid crystal panel, the liquid crystal panel constitutes the LCD device with a backlight unit.
The array element on the first substrate includes a switching element such as a thin film transistor (TFT) and various conduction lines which are formed of laminated layers of a conductive material, a semiconductor material and an insulating material. FIG. 1 is a perspective view showing an array substrate of a liquid crystal display device according to the related art. In FIG. 1, a gate line 26 and a data line 21 are formed on a substrate 12. The gate line 26 crosses the data line 21 to define a pixel region P. A thin film transistor (TFT) T is connected to the gate line 26 and the data line 21 and a pixel electrode 20 in the pixel region P is connected to the TFT T. A data pad 24 is formed at one end of the data line 21. Although not shown in FIG. 1, a gate pad is formed at one end of the gate line 26.
After the array substrate is completed, a visual test step where the array substrate is inspected with a naked eye of an operator is performed. For example, defects of the patterns and openings of the conductive lines may be detected in the visual test step. When the defects and the openings of the array substrate are detected, the positions corresponding to the defects and the openings are marked and an intensive test step for the array substrate is performed.
In the intensive test step, a real operational environment applied to the LCD device is required for more accurate result. Since the liquid crystal panel does not include a light source, the backlight unit is disposed under the liquid crystal panel to display images. In addition, the liquid crystal panel, the backlight unit and the driving circuit unit constitute the LCD device. Accordingly, light and heat from the backlight unit and heat from the driving circuit unit are supplied to the liquid crystal panel during the operation of the LCD device. As a result, it is required for the exact result of the intensive test to apply the real operational environment such as the light and the heat to the array substrate. Further, an apparatus for the intensive test is required to have an illuminating unit and a heating unit to apply the real operational environment to the array substrate.